Add tests for clears, render passes, framebuffers (#107)

* Add tests for clears, render passes, framebuffers

* Test load with a draw in it

src/backend/Framebuffer.cpp

@@ -103,19 +103,10 @@ namespace backend {
             return nullptr;
         }
 
-        // TODO(kainino@chromium.org): Remove this flag when the
-        // null=backbuffer hack is removed. Then, using null texture views can
-        // be completely disallowed.
-        bool usingBackbufferHack = false;
         for (auto& textureView : textureViews) {
             if (!textureView) {
-                if (usingBackbufferHack) {
-                    // TODO(kainino@chromium.org) update this too
-                    HandleError("Framebuffer has more than one null attachment");
-                    return nullptr;
-                }
-                usingBackbufferHack = true;
-                continue;
+                HandleError("Framebuffer attachment not set");
+                return nullptr;
             }
 
             // TODO(cwallez@chromium.org): Adjust for the mip-level once that is supported.

src/backend/RenderPass.cpp

@@ -94,6 +94,23 @@ namespace backend {
             }
         }
 
+        for (const auto& subpass : subpasses) {
+            for (unsigned int location : IterateBitSet(subpass.colorAttachmentsSet)) {
+                uint32_t slot = subpass.colorAttachments[location];
+                if (TextureFormatHasDepthOrStencil(attachments[slot].format)) {
+                    HandleError("Render pass color attachment is not of a color format");
+                    return nullptr;
+                }
+            }
+            if (subpass.depthStencilAttachmentSet) {
+                uint32_t slot = subpass.depthStencilAttachment;
+                if (!TextureFormatHasDepthOrStencil(attachments[slot].format)) {
+                    HandleError("Render pass depth/stencil attachment is not of a depth/stencil format");
+                    return nullptr;
+                }
+            }
+        }
+
         return device->CreateRenderPass(this);
     }
 

src/backend/opengl/CommandBufferGL.cpp

@@ -97,6 +97,11 @@ namespace opengl {
                     {
                         commands.NextCommand<BeginRenderSubpassCmd>();
 
+                        // TODO(kainino@chromium.org): This is added to possibly
+                        // work around an issue seen on Windows/Intel. It should
+                        // break any feedback loop before the clears, even if
+                        // there shouldn't be any negative effects from this.
+                        // Investigate whether it's actually needed.
                         glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
                         // TODO(kainino@chromium.org): possible future
                         // optimization: create these framebuffers at